Scientists at Duke University, USA have successfully restored the production of dystrophin protein in cultured muscle cells using a new technique called gene editing.
Dystrophin is the protein missing in people affected by Duchenne muscular dystrophy. Its role is to protect the muscle cells from damage when they contract.
The researchers extracted myoblasts from people affected with Duchenne muscular dystrophy and cultured them in the laboratory. Using the gene editing technique called CRISPR/Cas9, they have managed to restore dystrophin production in these cells. In order to test whether the cells are able to re-settle in the body, the scientists re-implanted them into the muscle tissue of mice and saw that they were capable of making human dystrophin protein.
CRISPR/Cas9 is a natural system that is present in bacteria as a defence mechanism against viruses that infect them. Bacteria have special proteins, or molecular scissors that recognise and cut the DNA of the invading virus. Scientists have made use of this system and engineered it to target their gene of interest.
In the case of Duchenne muscular dystrophy the CRISPR/Cas9 machinery is directed to the dystrophin gene and cuts out the region that is mutated. This means that a shorter but still functional dystrophin protein can be made.
The aim of this approach is to restore the mistake in the dystrophin gene and transform Duchenne muscular dystrophy into Becker muscular dystrophy. Becker muscular dystrophy is characterised by a shortened dystrophin protein and is a much milder condition. Most people affected might not have any significant effect throughout their lives.
The advantage of this approach is that it could benefit more than 60 percent of people affected with Duchenne muscular dystrophy as it targets a large region of the dystrophin gene, between exons 45 and 55, which is a region where most mutations occur. Moreover, directly targeting the gene to repair it removes the need to repeatedly give foreign biological material to patients and could potentially even be a cure one day. However the technique does not work very efficiently at the moment.
Duchenne muscular dystrophy is a devastating muscle wasting condition mainly affecting boys. It is thought that there are 2500 people living with the condition in the UK. There are currently no known treatments or cures.
Dr Marita Pohlschmidt, Director of Research at Muscular Dystrophy UK said: This is a very exciting new approach and the results of the experiments are encouraging. Even though a lot more research is required on the efficiency of this system before it can even be taken to the clinical trial stage, the CRIPSR/Cas9 gene editing approach offers an exciting opportunity for the treatment of a large proportion of Duchenne muscular dystrophy cases.
Muscular Dystrophy UK has been funding research towards finding a treatment for Duchenne muscular dystrophy as well as other muscle wasting conditions for over 50 years.
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